For which of the following assignments do soldiers incur all costs?

The correct choice clarifies that for exchange assignments, soldiers incur all costs associated with their assignment. This includes expenses related to travel, living arrangements, and any other necessary expenditures while serving in a different duty station or with a different unit. The nature of exchange assignments involves a mutual agreement between different service branches or commands, and as part of the terms, soldiers must often cover the costs involved, as these assignments are intended for professional development and broadening experiences rather than standard duty.

In contrast, other types of assignments typically have different logistical support structures or financial regulations. For example, compassionate assignments are typically initiated for personal or family-related reasons and often have cost considerations covered by the military. Mandatory assignments are required based on the needs of the service and agreements can be arranged to provide financial support for those involved. Voluntary assignments may involve some financial support, depending on the specifics of the situation and the policies in place. Thus, understanding the unique financial implications of exchange assignments is crucial for soldiers considering this option.